Telegraphy.



T. B. DIXON.

TELEGRAPHY.

APPLICATION mm AUG. 22, 1910. mznzwzo JAN- 24. 1916,

1 1 97,46 1 Patented Sept. 5, 1916.

4 SHEETS -SHEET l.

/NVENTOR A TTOHNEY T. B DIXON.

TELEGRAPHY.

APPLICATION FILED AUG. 22, 17910. RENEWED JAN. 24. I916.

PatentedSept. 5,1916.

4 SHEETS-SHEET 2- wmm,

ffyv I l I E I l I l I I I //v VENTOH m pr ATTORNEY T. B. DIXON.

' TEfEGRAPHY. APPLICATION FILED AUG.22. 1910- RENEWED JAN-24,1916.

1 ,1 WAI Patented Sept. 5, 1916.

4 SHEETS-SHEET 3.

T; B. DIXON.

TELEGRAE'HY.

APPLICATION FILED AUG.22, 1910. RENEWED JAN- 24.1mm

Patented Sept. 5, 1916.

4 SHEETS-SHEET 4.

Inventor: mam

A tty UNITED srAT s PATE OFFICE.

rnonms n. nrxorr, on NEW roan, N. Y.

rnnncnarnr.

Specification of Letters Patent.

Application flle'd August 22, 1910, Serial No. 578,277. Renewed January 24, 1916. Serial No. 74,064.

To all whom it may concern: v

Be it known that I, THOMAS B. DIXON, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telegraphy; and I do hereby declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to telegraphy and comprises a novel system and apparatus particularly adapted for use on circuits of great retardation, such for example as long submarine cables.

For various reasons it is now customary to transmit messages over such circuits by dots and dashes which are distinguished from each other by relative positionwith respect to a variable zero; practical difliculties having prevented transmission, over long lines of high retardation, by means of dots and dashes, which are distinguished from each other by relative duration, as, for ex ample, in the Morse system commonly used in land line telegraphy; notwithstanding the fact that the practical superiority of transmission by dots and dashes, distinguished from each other by relative duration, where such system is practicable, is

well recognized. In the present system I have overcome the practical difficulties which have hitherto substantially prevented transmission, through lines of great retardation, by dots and dashes distinguished from each other by relative duration, instead of by relative position with respect to a zero. In my said system the transmitting means employed may be of familiar character, be-

ing preferably a machine transmitter Whereby dots, dashes and spaces of standard lengths may be transmitted with uniformity; though hand transmission is not precluded. The receiving apparatus comprises an actuating element (specifically, in the ap paratus hereinafter described, a delicate refleeting galvanometer) arranged to vary the action of a beam of radiant energy (specifically, a light beam) on a radio-electro-sensitive element (specifically, a selenium cell or group of such cells); such radio-electrosensitive element in turn controlling a delicate relay, which customarily itself controls a sounder, recorder, repeater, or other suit referred to involving the use of radio-electro-sensitive elements as described, in the transmission of messages by means of dots and dashes difierentiated from one another by relative duration, trouble has been experienced heretofore from a so-called variable lag, the reason for which will be explained hereinafter, and the result of which is to unduly shorten or clip dashes, and spaces greater than dots. In general, it may be said that such distortion of dashes and long spaces is due to the fact that, the coil of the line galvanometer being deflected a greater distance for dashes orlong spaces than for dots or short spaces (hereinafter v termed element spaces), said coil in its return movement tends to move, somewhat like a pendulum, with greater velocity, following such dashes or long spaces, than following dots or element spaces. To obviate this difliculty, according to my present invention, I provide, in connection with the said line galvanometer, variable retardation or damping means, controlled by a time element, for the purpose of making the velocity of return movement of the coil, or, at least, of its reflector, substantially the same in all cases whether the preceding signal has been a dot, or a dash, or a short or a long space.

The fact that, in telegraph systems in which the several signals are distinguished from each other by relative duration, these signals (dots, dashes, or long or short spaces) have definite relative standard durations, which are particularly regular when machine transmission is employed, makes it practicable, and, by the means hereinafter de-' scribed, particularly easy, to compensate automatically for the tendency of the galvanometer coil to return with .varying velocities following signals of varying durations. In

this way I am able to provide a very efiec tive working margin since when the compensating means referred to is employed, the adjustment of travel of the beam of radiant energy may be such that said beam will travel over the entire width of the radio electro sensitive element, or group of such elements, employed, for each signal, so that said element works at all times at its maximum eificiency.

10 In this specification I have illustrated and described selenium cells asspecific examples of radio-electro-sensitive elements, or radioelectric current varying devices, whlch may be employed, without limiting myself, however, from the employment of other radio-.

electric current varying devices, whether operated by lightrays,-heat rays, or other form of radiant energy, and whether the action of such rays be to increase or decrease the resistance of the substance employed;

and I have illustrated and described a refleeting galvanometer as the actuating device for such radio-electro sensitive element,

or radio-electric current varying device,- without intending'thereby to limit'myself to any particular type of actuating device for thepurpose. 1

The objects of my invention are to improve telegraph systems and apparatus, particularly systems and'apparatus adapted for use on circuits of high retardation; to make practicable in such circuits, transmission by dots, dashes and spaces distinguished from each other by relative duration; to increase the speed of transmission over such circuits;

to increase the certainty of transmission over such circuits; to make the signals received more legible and more easily read or interpreted; to provide for automatic and reliable 40 repetition of messages from one circuit to fro movement of said mirror'so that it will always deflect the light beam controlled by it between certain predetermined limits only. even though the. movements of its actuating coils vary widely with respect both to amplitude and velocity; to provide an improved arrangement of circuits and batteries for the selenium cells and the primary of the transformer or induction coil, whereby large current values in the secondary of said coil may be obtained; to provide an improved receiving instrument combining a telegraph ink marker, relay and time element arranged to'equalize velocities of movement of the mirror; and in general, to simplify and improve radio-electric telegraph systems and ties at different times; to limit the to-and apparatus. These objects are attained in the system and apparatus herein described and illustrated more or less diagrammatically in the drawings which accompany and form a part of this "specification, in which:

Figure 1 is a diagrammatic-perspective view showing a cable circuit equipped with both transmitting and receiving apparatus,

the latter of a type embodying my present invention; Fig. 2 shows a front elevation of an instrument employed in said receiving apparatus and combining in a single structure signal receiving and repeating means and a time element for controlling themo'w tions of the galvanometer mirror; and Fig. 3 is a plan view of'the said instrument with certain of theparts removed; Fig. 4 shows a detail elevation of the contact mechanism of the said instrument, the view being taken looking from the left of Fig. 2; Fig. 5 is a detail perspective elevation ofthe support for the galvanometer mirror, showing par-- ticularly the bearings for the needle points employed as pivots for the saidsupport;

Fig. 6 shows a perspective. elevation of an; electric damping'device which may be employed, in connection with said mirror, as a drag. Fig. 7 is a diagrammatic view showing an alternative arrangement of'circuits of the damping device of Fig. 6; and Fig.

I 8 is a similar view showing a further alternative arrangement of such circuits; 9

is a diagrammatic view showing the control v of a relayby seleiiium cells andbatteries 'without the intermediation of an induction coil. Fig. 10 is "a diagrammatic view showing the control both of the retarding device of the mirror and the control of an electric drag, (such as shown for example .in Fig. 6) by the contact mechanism, of the time element or time train shown in Figs, 2, 3, and

showing the adjusting collars- 59..

Referring now to .Fig. 1, 1 is a pole changing transmittitng relay constituting,

.4: Fig. 11 is an enlarged detailed yiewr o in the diagram, adiagrammatic representation of transmitting means broadly, it being understood that the circuit'of the actuating magnet of this relay-will, in practice, be operated by a suitable circuit breaker, such as ahand key or'a machine transmitter of one of various well-known types; said'transmitting relay having a battery 2, of positive polarity, connected with its left or spacing conity, connected with its right or marking contact stop, and a battery 3, of negative polartact stop. The negative pole of battery 2 andthe positive pole of battery .3 are-connected to earth, as shown. A cablecircuit 4, having the usual condensers 5 at each end, I

is connected at the transmitting end with the lever of transmitter 1 and at the receiving end with the specially constructed reflecting galvanometer 6, passing through its actua ing coil 7 to earth. The coil 7 is provided with a torsional suspension, as shown, similar to the torsional suspension of the 0011 of a siphon recorder, whereby said coil is susmirror carrier 12 of mirror 13 and by a trace.

14 to a drag or yielding device 15, both 'mirror carrier and drag being arranged to turn on a vertical axis. This drag, in the form shown in the figure, consists of a light crossshaped object having two blades 16, each partly immersed in liquid contained in a reservoir 17. The mirror carrier 12 has at tached rigidly to its lower end a small coil 18 whose axis coincides with that of the mirror carrier and whose function; is to exert certain damping effects on the movements of the mirror and mirror carrier which will be fully described farther on. Coil 18 turns on its axis in a magnetic field produced by a magnet, the pole pieces 19 only of which are shown. Mirror carrier 12 and drag 15 are held firmly against needle points 20 and 21 by the taut traces 11 and 14, mirror carrier 12 and drag 15 each having, preferably, (see also Fig. 5) a bearing for the upper needle point shaped like a hollow cone, and having a vertical V-shaped lower bearing of considerable length, as shown in detail in Fig. 5. Constructing the upper and lower bearings in this way provides a support which prevents the drag and mirror carrier from gradually working downward by gravitation and also removes any difliculty in connection with needle points finding their centers. Obviously, the arrangement may be varied 'by placing the hollow cone bearings at the bottom and the V-shaped bearings at the top. -When actuating coil 7 turns on its axis, it will be seen that both mirror carrier 12 and drag 15 will be caused to turn with it through the action of traces ll and 14. I prefer to'connect the trace fibers closer to the axis of mirror carrier than fibers 9 are to the axis of coil 7, so as to obtain the eifect of causing the mirror carrier and the parts attached to it to have a comparatively large movement for a comparatively small movement of coil 7, the effect being the same in principle as if the coil transmitted motion to the mirror through multiplying gearing. I

prefer to connect the trace fibers of the drag in the same manner. The rotation of the mirror carrier is limited by'stop fibers 22 which are slightly slack when the mirror carrier is in the central position, one of them becoming taut and the other more slack as the mirror carrier turns on its axis from one extreme position to the other.

A beam 23 from a source .of light 24, concentrated by condensing lenses 25, and given, preferably, a rectangular shape with respect to its cross section by a screen 26 having a rectangular window, is projected against the surface of the concave mirror 13, from which it is reflected, thence passing through a Plano-convex cylindrical lens 27 to the faces of selenium cells 28. When the beam reaches the cells it is of approximately rectangular cross section, its size being such with relation tothe surface of the cells and the space between them that when the mirroris in the central position a half or thereabout of the total cell surface is illuminated while the other half is not. I prefer to always employ the selenium cells in pairs, or in a plurality of such pairs, (two such pairs being shown in the drawings), so arranged and connected electrically, as hereinafter described, as to cooperate to produce a cumulative effect in the circuit influenced by the variations in illumination of the cells.

In practice, the adjustment of the drag 15 is preferably such that it ofi'ers somewhat greater resistance to the motion of the galvanometer coil 7 than does the mirror carrier 12, and therefore when the galvanometer vanometer coil to move until it comes to rest naturally. In return movement of the galvanometer coil, the mirror begins to move as soon as the coil does, and continues to move until arrested by its other stop fiber 22, the drag 15 then moving and so permitting the galvanometer coil to continue to move until it comes to rest naturally. Th1s cooperation of the drag with the mirror and galvanometer coil permits the mirror to move throughout its entire range of movement for dots, dashes, or spaces, regardless of the variable duration of such signals and the consequent variable amplitude of movement of the galvanometer coil; the lmportance of which will be apparent later.

. \ia conductor 31 through the right hand cells, conductor 32, the left hand cells, conductor 33 to the negative pole of battery 29, through battery 29 and conductor 34 to the negative pole of battery 30.

35 is an induction coil or transformer having the terminals of its primary coil 36 connected to conductors 32 and 34 by conductors 37 and 38.

Assuming for the moment the position of v the light beam to be central so that the cells on each side are half illuminated and further assuming the cells on the right to be equal in resistance to those on the left and the poo tentials'of batteries Y29 and also to be equal, no current can flow through conductors 37 and 38 and'the-primary c011 of the induction coil since the potentials of the batteri es oppose each other as to coil 36. When,

' s'however, the light beam is deflected to the left from the central position, to the positionshown in Fig. 1, it fully illuminates the cells on the -left and does not illuminate those on the right, thereby decreasingthe resistance ofthe cells on theleft and increasing the resistanceof the cells on the right, the effect being to cause a flow, of current throughthe primary coil 36 via conductors 37 and 38, which will continue as long .as the resistances of the cells remain unequal. The rise of current flow through the primary of induction coil induces a current in the secondary coil 39 which passes via conductors 40 through the-actuating coil of relay 41'. Relay 41 responds to current reversals and consists of 'a coil of-fine wire delicately suspended or pivoted between the poles of a magnet and carrying a contact arm playing between contact stops, and

electricallyfcontrols the electromagnets 65 and .66 of recelving instrument43, fully described farther on, this instrument being shown diagrammatically only, in Fig. -1.

With the apparatus in the position indicated in the figure, the transmitter 1 is in the nor-- mal or spacing position, and a circuit from the positive pole of battery 2 is completed through the right contacts of transmitter 1,

. from battery cable circuit 4, and coil 7 of galvanometer,

'6 to earth, thence through the earth to the negative pole of the battery. The current 2 has turned the'c0il7 on its axis from right to left, this movement of the coil having moved mirror 13 from rightto left so as to deflect the light beam from right tov left, this'having caused'the resistance of selenium cells to vary, as abovedescribed,

and having caused a current from battery 29 to flow through the primary 36 of induction coil 35, and so having caused an induced current to flow through secondary coil 39 of induction coil 35, the contact lever of 5 to be understood that while the condensers coming taut, and carries drag 15 with it, the

result being to completely illuminate the cells on theright and leave those on the left without illumination. (It may be here pointed out, however, that the adjustment can be such, if desired, that while the cells on one side are fully illuminated those on the other side may remain partially illuminated.) This variation in illumination will cause a change in resistance of the selenium cells so that current from battery '30 will flow through the primary ofv the induction coil in opposite direction to that just described. It will be seen that thecurrent induced in the secondary of the induction coil will be the resultant of the total. variation of current of-the two batteries 29. and 30, being double what it would be, other things being equal, with a single battery and a single selenium cell or group of cells. The current induced in the secondary coil operates relay 41, causing its contact lever. to

make contactwith its right contact'point so as to interrupt the circuit of battery 42 and -=I1aagnet 66 and complete the circuit of .bat-

tery 42 and magnet 65. The return of transmitter 1 toits normal or spacing. position and the consequent operation of'coil 7 and "mirror 13 will cause the'light beam to again be deflected to the left, thereby illuminating the left group of cells and leaving those on the right unilluminated, the resistance variations in the selenium cells causing an induced current in the secondary of the induction coil of opposite direction to that resulting from the movement of the light beam from left to right, the efi'ect being to again operate relay 41 and return its contact le'-,

ver to its left hand or spacing position and to reestablish the circuit, of battery 42 through-magnet 66.

Before proceeding tion of apparatus illustrated in Fig. 1 it will be necessary to describein detail the receiving instrument 43, illustrated in Figs. 2, 3 and 4, which comprises means for recording and repeating the signals, also a time element controlling the damping of the galvanometer mirror. Referring now to these figures, 44 is a motor whose shaft 45 carries a worm 46 engaging with a worm wheel 47, the shaft having ,a bearing in support 48 which rests on a base .49.. Worm wheel 47 is keyed to a shaft 50 having bearfurther with descri bearings in supports 51 and 52. Shaft 57 carries two collars 59 and shaft 58 twocollars 60, the purpose of which is to permit of longitudinal adjustment of shafts as well as to hold said shafts in place. Supports 51 and 52 are shaped as shown in Fig. 2 more particularly, being hollowed out to allow spaces for the said gear wheels and collars. Shafts 57 and 58 each carry a drum of insulating material, the drum on shaft 57 carrying conducting rings 61 and that on shaft 58, conducting rings 62, said pairs of rings engaging respectively with two pair of brushes, 63 and 64, and connecting electrically with electromagnets 65 and 66 of two electric clutches, .which magnets are also mounted on shafts 57- and 58, the ends of the shafts being secured to the yokes of the magnets. The said drums, rings and magnets revolve with their shafts continuously owing-to the gear wheels which are driven by motor 44. Across the poles of magnets '65 and 66 are cross pieces 67 and 68 made of non-magnetic material, the function of these cross pieces being to furnish bearings for journals 69 and 70 of a shaft 71. The shaft 71 has keyed to it near its ends two disks, 72 and 73, which may be of non-mag netic material, and which have fastened to them soft iron rings 74 and 75, these rings having, preferably, a thin film of non-magnetic material, on their sides next their magnet poles, for the purpose of overcoming the effects of residual magnetism and thereby making the instrument capable of more rapid operation. Magnet 65 and ring 75 constitute an electric clutch for transmitting motion from shaft. 57 to shaft 71, and magnet 66 and rin 74 constitute a simi: lar electric clutch for transmitting motion from shaft 58 to shaft 71. Shaft 71 also carries two collars 76, .adjustable longitudinally, and a contact'lever 77, shownin detail in Fig; 4. This lever'is not made fast to shaft 71 but is held against it by a spring 78, the resulting friction being sufficient to cause the lever to turn with the shaft,in the dlrection indicated by dart, when the shaft turns, against the tension of retractile spring 79, whichis attached to lever 77, and to an adjustment screw which is mounted on a beam .81, of insulating material, the beam resting on supports 51 and 52. Lever 77 is normally drawn upward by spring 79 and rests against a roller 82 having bearings in a lug 83 which projects from apost of insulating material 84. A contact lever 85, pivotally mounted on a lug 86 attached to post 84, is pulled upward normally by a spring 87, the upper end of which is held by an adjustment screw 88 mounted on beam 81. The upward travel of lever is limited by a stop screw 89. The downward movement of lever 85 as well as of lever 7 7, is limited by a contact screw 90 carried by a conducting piece 91. Lever 77 is connected electrically by means of a wire 92 with a binding post 93, contact screw 90 is connected by means of pieces 91 with abindin'g post 94, and lever 85, by means of lug 86, with a binding post '95. It will be seen that a downward movement of lever 77 due to turning with shaft 71, ifcontinued long enough, will cause the contact point of the lever to' engage with the upper contact point of lever 85, whereupon lever 85 will be carried downward until, if the movement continue long enough, lever 85 engages with stop 90, when its motion, as well as that of lever 77 will be arrested, the action of spring 7 8, however, permitting shaft 71 to continue revolving. V

96 andv 97 are flat clutch springs mounted on beam 81 ,and the lower ends of which press against the hubs of disks 72 and7 3, respectively, spring. 96 tending to move disk 72 from right to left so as to carry to the left shaft 71 and the members fixed thereto with it, spring 97 acting similarly but in the reverse direction and pressing against the hub'of disk 73. The function of these springs is to assist in overcoming the inertia of shaft 71 and the members carried by it in its longitudinal movements.

carries two contact points adapted to makecontact alternately with contact stops 100 and 101. The end of horizontal lever 991 is wedge shaped and engages with a jockey 102 which tends to holdsaid lever firmly against whichever contact stop it maybe in contact with. Lever 99 carries a siphon tube 103, the upper end of which dips in an ink reservoir 104, its lower end as. it moves up and down with an arm 991 making a record of the signals on a strip of moving" tape 105 which is guided bya roller 106 and spring 107 attached tolugs of support 52,- the tape being pulled from right to left by' two revolving rollers 108 driven by a suitable motor, not shown. Lever 99 is con nectedby a wire with a binding post 109,

contact stopsl00 and 101 to binding posts 110 and 111 respectively, and the signals may be automatically repeated, where required, by means of lever 99 and contact points 100 and 101, the circuits for repeat .ingthe signals into a second cable 115 being shown in Fig. 1. The two outer brushes of brushfpairs 63 and 64, respectively, connectwith' binding posts 112 and 114, and

' i will. be attracted to thepoles of saidinag-- net, turning Witlloit andputting spring .96

the two inner brushes; with a common bind ing post 113, as. shown.

'Normally, motor 44 causes shaft-O and gear wheels 53 and-.54 to rotate in the di-.,

and 5.6 and members rotated by them turning in the opposite direction, as indicated by the upper group. of darts.

In-the drawings it is assumed thatlnagnet '66 has just been energized by current from battery 42, (see Fig. 1) so that ring 74 is attracted to and :held firmly by its poles. This will cause the ring-to start to.- revolve with the magnet and carry with it lever 77 which, if the magnet remain energized for a, sufiicient time, will make contact with lever 85 and carry said lever with it until both levers are stopped by. stop 90, afterwhich, if the magnet still remain energized, ring 74'wi'll continue to turn with the magnet, the action of spring 78 permitting this. As'soon as magnet 66 is d'energized, owing-to. the; operation of relay 41,; spring- 97- will act to. move the ring 74 away from the poles of themagnet, and springs 79 and 87 return; \levers 77 and 85' to their normal positions; and when magnet becomes energized the ring in a; tate of tension, and causingshaft to rotate and so to move lever 77 into con- 3 tact with. lever 85, and then tormove thetwo levers together, provided, "magnet 65 remains energized long enough. When magnet 65 is again. 'denergized spr ng .96 causes shaft 71 to start to move from right Q to lett, magnet 66v again attracting ring 74' assoon as. renergized' so. as-to complete the travel ot-the shaft. llhis arrangement of agnets and springs for operatingshaft 71 is extremely eflicient since the springs act at 5 the moment the rings are released and at a time. when the magnetic pull fromthe opp s te m gn t sv k st-ow ng -"d ta I p e its motion and resistances 116. and It wilt now be clear that the a.pparatus.; 11'i 9.' may. be so adjusted that if a series of dots j only-be sent over the line circuit the shaft 71 -and .rnembers attached to it will vibrate from its ring.

' longitudinally betweenthe poles of'magnets 11 66,. and that-the speed of the drivi .5 mg motor44 may bev such that for dots and thes'element spaces following them lever 77 will always-be released and. returned; to: nor-. mal befiore itcan move far enough to engage with lever 85, but that for dashes, magnet ?9 65 being then'energized for a longer time than it is for dots, the lever-will move downward sufiieiently. toengage with lever before being released and returning tonormal.

Alstathat. for the longer Spaces, which are -.usually of; two kinds, letter-and word, the

now, adash besent'so. that lever 77 moves would do if free, responsetothe spacing "effect of the self induced currents of coil 18 w ll so reduce the-velocity of movement former generally having the length of the dash, while the latter has something like that the effect of spacing currents sent over the line or cable circuit is always to energize magnet 66 while that of marking cur rents isto energize magnet 65-, it will be ap-. parent that if it should be required that dashes and letter spaces be of different lengths this result may be easilyobtained by making the gear ratio of the gear wheels 53' and 55, and 54 and 56, unequal, these being shown as equalin the drawings. The adjustment for word spaces is obtained in any case by means of stop screw .96.; t v

Referring again to Fig. 1, and assuming first that a regular series of dots are being sent over the line, the contactlever of relay 41 will vibrate regularly between its. contact a 9 1* longitudinal vibration of shaft 71 and the members carried by it produci no .eflect respecting the signals other than the recording of thedots on the tape and their repeti'-. tion into the second cable. circuit, 115. If,

far enough to make contact with lever 85, resistances 116 and 117 are cut into the circuit of coil 18, this coil being normally shunted by a high resistance 118., Atthe termination of the dash, assumin forqthe moment that resistances 116/ and l t had not been out in, the coil 18- and mirror'wou ld retunn'to their spacing side with a much higher velocity-of movement than for'the spacing interval following a dot of the series just assumed, but the cutting in of resistances-116v and 117 has .the effect of cansing coil 18' to move more slnggishly, than it current following the dash, owing to. the selfinduced currents of coil 18 tending to,

are soproportioned that the damping of. the coil that itfwill be the sameor approximately the same for the space following'the dash asforthe spacesfollowing dots. Assuming the. dash to have terminated and:

a letterfspace to bathe next sent, lever 77 will have-returned to normal and/with the renergi zing of magnet 66- lever .77' will agam make contact, before the termination of the letter space, with lever 85, so: as to again out resistances 116 and 117 into cir-. 'cuit with coil 18, the. efi'ect being to. cause coil 18 tomove withthe' samerelative slugglshnessat. the termination of the letter space as at the termination ofthe dash just 136.:

described. If, after a dot or dash, a word space be sent, the levers 77 and 85 will move until lever 85 engages with contact stop 90, the result of this being to short circuit resistance 116, and since this will reduce the total resistance shunting coil 18 still more,

the coil would tend to move more sluggishly after the termination of a word space than after the termination of the dash or letter space, but for the fact that the-coil 7 tends to move with much greater velocity follow: ing a word space than it does following a dash or letter space, just as it tends to move with much greater velocity following a dash or letter space than it does following a dot. The greater damping efi'ect following a word space Will, therefore, only have the effect of causing the velocity of move ment of coil 18, etc, to be approximately the same following a word space that it is following a dash or letter space, provided that the resistances 116 and 117 are properly proportioned to each other.

'Owing to the detrimental effects of variable lag in the circuits of relay 11, fully described farther on, it is highlyimportant that the velocity of movement of the light beam, as it sweeps over the faces of the selenium cells, shall be as nearly as possible the same for all signals. I, therefore, so proportion resistances 116 and 117 that they will exercise just enough damping effect on coil 18 to insure vits moving always with approximately the same velocity irrespective of the tendency of actuating coil 7, to move with greater Velocity. after dashes or word spaces than after dots or element spaces, the drag 15 moving with increased velocity when coil 18 exercises its damping effect. Shunt 118 is intended to exercise only a very slight but a constant damping effect for the purposeof steadying the mirror against any false movements due to vibration of supports or other cause.

I will now describe the variable lag above referred to. This, unless compensated for in some way, tends to shorten, or clip, the dashes and longer spaces of the Morse code in their reproduction on a relay or other receiving. device controlled by'radioelectric apparatus such as that herein described' To operate any relay the current must first reach a certain minimum value,

this value being generally termed the fig ure of merit of the instrument. Where the current or current variation resulting from the variation in resistance of a selenium cell due to changesin-illumination is utilized to operate a relay or other receiving device a serious difiiculty is encountered, unless compensating means, such as above described, for example, be employed, because of the fact that the resistance variation, and consequently the current variation, lags behind the variation in illumination, requiring some time to reach its final value. If, there fore, with a given change in illumination taking place in a given time, there is a certain lag in the relays response, it follows that with a greater change in illumination taking place in the same time, or with the same change in illumination taking place within a shorter time period, the lag is correspondingly less. Taking, for example, the velocity of movement of light beam 23 for the element space following a dot as a standard for comparison, it is found that, if no compensating means be employed, the

velocity of movement of the beam for the described all detrimental effects of variable lag are entirely eliminated, the velocity of movement of the light beam being practically the same, after dots, dashes, or spaces, long or short, of the standard lengths used in telegraph transmission.

Instead of using a liquid drag such as shown in Fig. 1, I may use various other forms of drag, for example, a magnetic drag such as shown in Fig. 6. The construction of this magnetic drag is very similar to that of the damping device of the mirror sup port 12, and comprises a coil 119 mounted to move through a magnetic field produced by magnet 120, the terminals of this coil being shunted through a variable resistance 121. It will be apparent that by varying this resistance 121, the strength of the currents induced in coil 119 by the movement of said coil through the magnetic field, which currents tend to oppose the movement of said coil, may be varied as desired, and so the retarding influence of this magnetic drag may be varied as desired.

In Fig. 7 I show an alternative arrangement of circuits for the damping coil 18 of the mirror. In this figure, 122 designates a battery for coil 18 having a resistance 123 1n clrcuit. such resistance 123 being shunted by a greater resistance 124:. Normally battery 122 and resistance 123 are not in circult with the coil, since the circuit of said battery is connected to the stop screw 90; the circuits of the coil 18 comprising resistances 116 and117 and a shunting resistance 118, and being controlled by contact levers 77 and 85, in the manner previously described with reference to Fig. 1. When contact levers 77 and 85 are brought into electric connection with stop 90, as they are when a word space or long dash occurs, battery 122 is cut into the circuit of coil 18, a portion of the current from this battery supplementing the damping effect of the self induction of coil 18, by tending to cause the coil to rotate in a direction opposite that in which galvanometer coil 7 tends to move it. In this arrangement of circuits shown in Fig. 7, resistance 116 is cut out of circuit during transmission of dashes and letter spaces, as described with reference to Fig. 1.

In Fig. 8 I show a further alternative arrangement of circuits for the damping coil 18 of the mirror, wherein two batteries 125 and 126,'each provided with a resistance 123 and shunted resistance 124, as described with reference to Fig. 7 are employed in local circuit controlled by contact points of lever 991; the one battery or the other, of batteries 125 and 126, being in the circuit of coil 18, according to the position of said lever 991; these batteries being of opposite sign. Resistances 116 and 117 are employed the same as in Fig. 7, and such resistances are controlled in the same way by contact levers 77 and 85. It will be seen that in this circuit arrangement, the current of one bat- ..ment of such coil during markmg movements of the mirror.

In case, during transmission of signals in the system, as above described, it becomes necessary to change the normal rate of transmission, so changing the absolute length of dots, dashes and spaces, the speed of motor 44 will be correspondingly changed and the damping action of coil 18 will be readjusted, if necessary, by adjustment of its controlling resistances, in accordance with the new absolute length of dots, dashes and spaces; also, if necessary, screws 89 and 90 will be adjusted.

From what has been said previously, regarding the relative actions of the galvanometer coil 7, mirror 13, and drag, it will be clear that the mirror begins to move as soon as the coil 7 begins to move, whether the coil, at the beginning of such movement, is at its central position, or at any other position, and that the permitted travel of the mirror is preferably such that, even for the shortest dots to be transmitted, the beam of light will move from one extreme position to the other, and will there remain until the galvanometer coil starts its return movement, whereupon the beam of light will move back to its other extreme position. Since the movements of the beam of light are the same in amplitude for dots, dashes,

or spaces of whatever light, and since these movements begin with the beginning of movement of the galvanometer coil, whatever be the position of that coil at the beginning of such movement, it will be clear, that my improved receiving instrument adjusted as described, is free from disturbances due to variation of the zero of the cable line, and therefore that the inductive control of the relay 41 by the radio-electrosensitive element or elements'is unnecessary. Therefore'in Fig. 9 I have indicated circuits for-the direct control of relay 41 by the radio-electro-sensitive elements 28, which circuits are the same as the correspondingcircuit shown in Fig. 1, except that the in duction coil is omitted, circuit conductors 37 and 38 leading direct to the armature coils of relay 41.

In Fig. 10 I illustrate how the contact mechanism of the time train shown in Figs. 2, 3 and 4 may control simultaneously both the retarding or speed-controlling device of the mirror 13, and an electric drag such as shown in Fig. 6. The contact mechanism of the time train, indicated diagrammatically in this figure, is the same as shown in Fig. 4 and as illustrated diagrammatically in Figs. 1, 7 and 8, except that for the contact stop 90a spring actuated contact lever 90 is substituted; this contact lever 90 being arranged to coact with a contact stop 127. The circuits whereby the retarding device of the mirror is controlled are substantially the same as above described with reference to Fig. 1. Coil 119 of the electric drag is included in a circuit 128 containing a suitable resistance 129 and passing through con- 7 tact lever 85 and a contact point 130 co-acting therewith. This circuit is shunted normally by a high resistance 131, and also by another circuit 132 passing through lever 90 and its stop 127, and containing a further resistance 133. It will be seen that, with the parts arranged as described, during the transmission of a dash or letterspace, resistance 129 is cut out. of the circuit of coil 119 by the coming together of levers 77 and 85 and consequent breaking of contact between lever 85 and contact 130; the resistance which coil 119 offers to the motion of the galvanometer coil to which the drag is connected being thereby reduced. It will also be seen that durin long dashes or word-spaces, when lever 7 moves lever 85 into contact with lever 90 and breaks connection between lever 90 and stop 127, circuit 132 is broken and so resistance 133 is cut out of the circuit of coil 119, leaving said coil shunted only by resistance 131. It follows from this arrangement that the drag offers maximum resistance, and so causes maximum movement of the reflector 13 in proportion to the movements of the galvanometer coil 7, following dots and element spaces; that following dashesand letter-spaces the resistance offered by the drag becomes less as the resistanceofi'ered to the movement of the reflector 13'becomes greater; and that this condition obtains to still greater extent following transmission of long dashesor word-spaces. The two moving coils, 18 and- 119, therefore, cooperate, through the equalizing fiber connection illustrated in Fig. 1, to control as'desired the speed of movement of the reflector without limiting materially the movement of the galvanometer coil 7; for as the resistance to the movement oficoil 18 becomes greater the resistance offered by the drag 119 becomes less.

The following is a brief description of the operation. of my improved telegraphic receiving apparatus, as illustrated particu-' larly in Fig. 1: First, assuming that transmitter 1 isin the normal or spacing position and that the light beam is to the left so as to illuminate the left hand group of selenium cells, the closing of the control ling circuit of this transmitter will take battery 2 from the line circuit and will connect battery 3 to that circuit, thereby reversing the polarity of the line circuit and causing the coil 7, mirror 13 and drag 15 to turn from left to right, so as to reflect the light beam 23 from left to right, until the move ment of the mirror 13 is arrested by one of the stop fibers 22. The movement of the light beam causes a current variation in the primary of induction coil 35, this current variation inducing a current in secondary coil 39 of proper direction to operate relay 41, causing the contact lever of said relay to leave its left hand or spacing contact stop and to make contact with its right hand or marking contact stop, thereby breaking the circuit of battery 42 and magnet 66 and completing the circuit of said battery through magnet 65, thereby closing one of the electric clutches of the time train, and

operating lever '991 and the ink marker carried thereby so as to record the signal on the tape 105. The opening of the controlling circuit of transmitter 1 will cut out battery 3 and will reestablish the circuit of battery 2 in the line, the light beam being again reflected to the left, causing a variation of current in the primary of induction coil 35 which will induce a current in the secondary of that coil of proper direction to deflect the armature of relay 41 to the left or to its spacing contact point, magnet 65 being thereby deenergizedand magnet 66 being energized, thereby opening the clutch of the time train previously closed and closing the clutch of that time train controlled by magnet 66, besides again operating lever 991 and raising its ink marker from the tape 105. In case either a marking signal or a spacing signal continues beyond the predetermined length fora dot or'element space, contact will be closed between con-v tact lever 77 ofthe time train and contact lever 85 thereby increasing the resistance offered to the motion of the mirror, 13, during further movement of said mirroryand if either a marking-or a spacing signal continues beyond the predetermined duration for an ordinary dash or' letter-space, contact will be closed between lever 85 and contact 90, thereby increasing still further the resistance offered by coil 18 to the motion of the mirror 13.- By the means described, the velocity of movement of the light beam is caused to be always approximately the same for all signals, regardless of varying amplitude of movement of the galvanometer coil 7, but without interfering With freedom of motion of the ganvanometer coil 7 to the extent determined by the strength and duration of the current pulses operating said coil. Distortion of signals due to varying lag of the circuits controlling relay 41 is thereby eliminated and distortions due to varying zero of the cable line 4, such as might exist if the motion of the galvanometer coil 7 were materially restricted, are avoided.

In the following claims I use the term illumination in a broad sense to include the actions of radiant energy rays of any character on the radio-electro-sensitive device; in other words, the word illumination is used to include the action of heat rays and other radiant energy rays, as well as light rays.

What I claim is 1; The method of reproducing telegraphic electric signals, transmitted through a circuit of great retardation and distinguished in character by difference in duration, which consists in causing said signals to vary the action ofradiant energy on a radio-electrosensitive element in an electric circuit, and causing the electric quality of said, element to begin to vary at substantially the same point in all signals, and to vary at approxi mately the same rate foreach signal, Without regard to variation of duration of the different signals.

electric signals, transmitted through a cir-jfl, c.

' cuit of great retardation and distinguished in character by difference in duration, which consists in causing said signals to vary the action of radiant energy ona radio-electrosensitive element in an electric circuit, and:

causing the electric quality of said element to vary at approximately the same rate and i to approximately the same extent for each signal, without regard to variation of durav tion of the different signals.

3. The method of reproducing telegraphic electric signals, transmitted through a circuit of great retardation and distinguished I or a spacing sig al, and y the resulting in character by difi'erence in duration, which consists in causing said signals to move a beam of radiant energy across the surface of a radio-electro-sensitive element in an electriccireuit, and causing thearea of such surface exposed to said beam to vary, during movement of said beam, andcausing said beam to begin to move at substantially the same point 'in all signals and to move at approximately the same rate for eachsignal, without regard to variation of duration of the difi'erent signals.

p 4. The method ofreproducing telegraphic electric signals transmitted through a circuit of great retardation and distinguished in character by difiierence in duration, which consists in causing said signals to move a beam of radlant energy across the surface or a radlo-electro-sensitlve element in an surface exposed to said beam to vary, during movement of said beam, and causing said beam to move at approximately the same rate and to approximately the same extent for each signal, without regard tovariation of duration of the different signals;

5. The method of reproducing telegraphic electric signals, transmitted through a circuit of great retardation, which 'consistsin causing eachof said signals to change the illumination of a radio electro sensitive element included in an electric circuit, from substantially complete'illumination to substantially no illumination, or vice versa, according as the signal be awmarking signal change in electric quality of the saidelement,

, effecting the. control of reproducing I means.

illumination of. one of two radio electroesenplete illumination to substantially noillumi nation, and to'change. the illuminationof the other said element from i substantially I noillumination to substantially complete illu-' mmatien, irrespectlve of variation 'of zero of the sad circuit, and by the resulting change in electric quality of said elements, efiectingthe control of the signal reproducing means.

7. In a radio electric relay, the combination of a' radio-electro-sensitive element, and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in air electric circuit, and having also another movable member separately mounted and'c'omprising means for varying the action of radiant energy on said radio-.electro-sensitive element, means connecting said members permitting motion of the. actuated member electric circuit, and causing the area of such- 6. The method of'reproducin'g'telegraphic electric signals,.,.transmitted.' through a. cir-' cu1t of great retardation, whichzconsists in' causing each of said signals toicha'nge the".

sitive elements, each of which, isfin'cluded in an electric circuit,.from substantially com after the second member has been arrested,

, and retarding means for retarding the motion of said second member.

' comprising means for varying the action of radiant ene gy on said radio-electro-sensitive elemen means connecting said members permitting motion of the actuated member after the second member has been arrested, retarding means for retarding the motion of said second member, and means regulating such retardation arranged to increase the retardation when the amplitude of movement of said actuated member 1s rela tively great.

9: Inna radio electric relay, the combinameans for varying the action of radiant Y the motion of said second member.

10. In a radio electric relay, the combination of a radio-electro-sensitive element,

and a 'galvanometer having an actuated member mounted in a magnetic field and controlledin its movements by signals in an electric circuit, and having also another :movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said members permitting motion of the actuated member after the second member has been and comprising means for maintaining the velocity of said member substantlally the same regardless of the variation in ampli- -,tude of movement of said first member.

11. In a radio electric relay, the combination of a radio-electro-sensitive element,

and a galvanometer having an actuated .member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying the action or radiant energy on said radio-electro-sensitive element, means connecting said members permitting motion of the actuated member after the second member has been arrested, and velocity-controlling means for tion of a radio-electro-sensitive element, and

a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said members pernritting motion of the actuated member after the second member has been arrested, retarding means controlling the motion of said second member, and timing means arranged to make the retardation greater for long signals than for short signals.

13. In a radio electric relay, the combina-v tion of aradio-electro-sensitive element, and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said members pe'rmitting motion of the actuated member after the second member has been arrested, retarding means for retarding the motion of said second member, a time train, and

means operated thereby for increasing the retardation if the signal exceeds a termined minimum in duration.

14. In a radio electric relay, the combination of a radio-electro-sensitive element, and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another predemovable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said members permitting motion of the actuated member after the second member has been arrested, retardingmeans for retarding the motion of said second member, a time train, and means operated thereby for increasing the retardation if the signal exceeds a predetermined minimum in duration and for further increasing the retardation if a signal exceeds a further predetermined limit in duration.

15. In a radio electric relay, the combination of a radio-electrosensitive element, and "a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said mem bers permitting motion of the actuated member after the second member has been arrested, electric damping means, controlling the motion of said second member, and comprising a coil arranged to move ina magnetic field, and means fordecreasing the resistance in the circuit of said coil when signals exceed a predetermined duration.

16. In a radio electric relay, the combination of---a radio-electro-sensitive element, and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying-the action of radiant energy on said radio-electrosensitive element, means connecting said members permitting motion of the actuated member after the second member has been arrested, electric damping means, controlling the motion of said second member, andbomprising a coil arranged to move in a magnetic field, and means for decreaslng the reslstance in the circuit of said coil When signals tion of a radio-electro-sensitive element,

and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and having also another movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitive element, means connecting said members permitting motion of the actuated member after the secondmember has been arrested, damping means for said second member comprising a coil arranged to move in a magnetic field with said second member, a time mechanism, and contact means controlled thereby arranged to decrease resistance in the circuit of said damping coil when a signal has exceeded a predetermined minimum.

18. In a radio electric relay, the combination of a source of illumination, a selenium cell, a galvanometer adapted to deflect a beam of light from said source of illuminaand means operated thereby for retarding the motion of 'saidsecond member when sigtrolled in its inovements by signals in an.

electric circuit, a second member separately mounted and comprising means for varying a galvanometer havmg an actuated member the action of radiant energy on a radio-electro-sens'ltlve element, a drag, and means connectlng said actuated member to said second member and to the drag comprising equalizing levers, tracesconnecting said levers to said actuated member, and traces connecting each said leverboth to the second member and to the drag. a

20. In' a radio electric relay, the combination of a radio-electro-sensitive element, and.

a galvanometer having an actuated member mounted in a magneticfield and controlled in its movements by signals in an electric 22. In a radio electric relay, the combinamounted to move freely in a magnetic field 55,

circuit, and having also another movable member separately mounted and comprising means for varying the action of radiant energy on said radio-electro-sensitiveelement, means tending to return said actuated member to normal position, a drag, means connecting saidactuated member both to said second member and to said drag, and retarding means for said second member.

21. In a radio electric relay, the combination of a radio-electro-sensitive element, and a galvanometer having an actuated member mounted in a magnetic field and controlled in its movements by signals in an electric circuit, and-having also another'movable member separately mounted "and comprising means for varying the actionof radiant energy on' said radio-eIectrO senSitiVe 'elcment, means tending to return said actuated member to normal position and exerting a variable tendency to that end according to the amplitude of movement of said actuated member, a drag, means connecting said actuatedmember both to said second member and to, said drag, retarding means for said second member, and means aifected by varying amplitude of movement of said actuated member, controlling said retarding means.

tionof a radio-electro-sensitive element, and a galvanometer havlng an actuated member and controlled in itsmovements by signals in an electriccircuit and provided with spring means tending to return it to normal position when deflected therefrom, said galvanometer also comprising a second member movably mounted and provided with means for varying the action of radiant energy on said radio-electro-sensitive element and with stops limiting its movement, connections between said second member and actuated member permitting free movemeaeci ment of the actuated member after movef 23. In a radio electric relay, the combination of a radio-electro-sensitive element, and

mounted to move freely in a magnetic field and controlled in its movements by signals in an electric circuit and provided with spring means tending to return it to normal position when deflected therefrom, said gal-- vanometer also comprising a second member 'movably mounted and provided with means -for varying the action of radiant energy .on said radioselectro-sensitive element and with stops limiting its movement, connection between said second member and actuated member permitting free movement of the actuated member after movement of said second member has been arrested, retarding means for said second member, and timing means controlling said retardingmeansin accordance with varying durati'on'of signals.

24. The combination of a radio-electrosensitive element, a galvanometer adapted to vary the action of radiant energy thereon and comprising retarding means controlling the rate of change of action of radiant energy, a relay controlled by said radioelectro-sensitive element, and a powerdriven mechanism, controlling the action of said retarding means, comprising electric clutch means controlled by "said relay.

25. The combinationwith a radio-electrosensitive element, a g'alvanometeradapted to vary the action of radiant energy'thereon and comprising electricall i-controlled retarding means controlling t change of action of radiant energy, a relay controlled by said radio-electro-sensitive element, contact means controlling said tarding means controlling the rate of change of action of radiant energy, a relay controlled by said radio-electrorsensitive element, contact means controlling said retarding means comprising a- -m'ovable contact member, a power driven member, and two electric clutches interposed between said power driven member and contact member, and controlled by opposite contacts of said relay.

27. The combination with a radio-e1ectroe rate 0t sensitive element, a galvanometer adapted to vary the action of radiant'energy thereon and comprising electrically-controlled retarding means controlling the rate of change of action of radiant'energy, said retarding means comprising a coil arranged to move in a magnetic field, a relay controlled by said rad-io-electro-sensitive element, contact means controlling resistance in circuit with said coil, and means for operating said con sensitive element, a galvanometer adapted to vary the action of radiant energy thereon and comprising electrically-controlled retarding means controlling the rate of change of action of radiant energy, said retarding means comprising a coil arranged to move in a magnetic field, a relay controlled by said radio-electro-sensitive element, contact means controlling resistance in circuit with said coil, and means for operating said contact means comprising two electric clutches controlled by opposite contacts of said relay, said contact means arranged to reduce the resistance in the circuit of said coil after either clutch has remained closed a predetermined length of time.

In testimony whereof I aflix my signature in the presence of two witnesses. v

THOMAS E. DIXON.

Witnesses:

WILLIAM B. SHELToN, H. M. MARBLE. 

